One class of fuel injectors are mechanically actuated via rotation of a cam shaft. As a cam lob rotates, a tappet is driven downward to push a plunger within the fuel injector to pressurize fuel for an injection event. After the cam lobe passes, a mechanical spring biases the tappet toward a retracted position to follow the cam surface as the cam continues to rotate. Prior to installation in the engine, there typically must be some means provided for preventing the biasing spring from causing the tappet to separate from the injector body during pre-installation handling. Known tappet retention strategies may utilize a pin such as that described in co-owned U.S. Pat. No. 6,209,798, or possibly a snap ring. Although these strategies have worked well, there remains room for improvement, particularly with regard to ease of assembly, robust operation over a long service life, and fuel leakage from the fuel injector around the tappet.
The present disclosure is directed toward one or more of the problems set forth above.